Developed by Dr. David Jenkins, a professor of nutrition at the University of Toronto, the G.I. measures the speed at which your body breaks down food and converts it to glucose, which is used for energy or stored as fat. When losing weight, it is critical to avoid foods that have a high G.I., because they are digested too quickly by your body. With Rick Gallop’s G.I. Diet you won’t have to calculate the glycemic ratings and calories because he has done that for you, by listing foods in one of three categories: foods to avoid, foods to eat occasionally, and foods that you can eat as much of as you want.